The treadmill, the elliptical, yoga, weights, lettuce, lettuce, grilled chicken, and more lettuce: It's the pre-filming routine of most stars.

But once in a very great while, all that gets swapped out for ice cream, doughnuts, and fried chicken. The couch gets a workout; the treadmill gathers dust.

Last week, Hugh Jackman revealed that he's consuming a whopping 6,000 calories a day to bulk up for his upcoming "Wolverine" movie on the advice of director Darren Aronofsky. Jackman usually tips the scale at 190 pounds; currently, he's 210, and looking to expand.

"[Aronofsky] said that Wolverine, in the comics, is powerful, stocky, you know, he's short and thick," Jackman told the Los Angeles Times. "So he said, 'I want you to go there, get bigger.'"

"Get bigger." In a culture obsessed with losing weight, it's a dream-like directive. Below, check out four more stars who have put on weight in the name of acting.

Before filming "Blue Valentine," Williams indulged in ice cream, and avocado sandwiches to pack more than 15 pounds onto her 5'4 frame. While Williams took her role as a woman in the midst of a crumbling marriage seriously, she and her co-star, Ryan Gosling, turned their mandatory munch-fest into a game.

"She ended up winning. She gained about 15, 16 pounds. He gained 14," "Blue Valentine" director Derek Cianfrance told People magazine in December. "Michelle was eating a pint of ice cream for breakfast and dinner, and avocado sandwiches all day. She wanted to do it. She talked about her character having a certain self-hatred."

Williams' ice cream of choice, according to Cianfrance: "stuff made with coconut milk," which can be more fattening than the milk and cream varieties. The extra calories seem to have paid off: Williams is up for a best actress Oscar for "Blue Valentine."

Hollywood Heavyweights

Zellweger endured two stints stuffing herself for "Bridget Jones' Diary" and its sequel, "Bridget Jones: The Edge of Reason." The 5-foot, 5-inch normally svelte star gained close to 30 pounds per movie by starting each day with a Big Mac and large fries, scones with gravy and a milkshake. After that, she'd scarf down peanut butter, pizza, spaghetti with meat sauce, butter-glazed potatoes and (gasp) more than a dozen doughnuts.

"I have to stick to it because I found out last time that one doughnut doesn't do a thing," she told Closer magazine in 2004. "You've got to eat 20 a day for five weeks before you get results."

While Zellweger was rumored to be holding up development of a third "Bridget Jones" movie for fear of going through the weight gain/loss process again, last year, her publicist insisted the actress would put on the necessary pounds should the film get the green light. But maybe Zellweger need not worry about shedding the fruits of her labor -- in 2001, reviewing the first "Bridget Jones," The New York Times noted that the actress looked "utterly real" with a bit more flesh on her bones.

Notorious for her rigorous fitness and diet regimens, Paltrow struggled to put on 20 pounds to play an alcoholic crooner in "Country Strong."

"The nightmare thing about it is I had to stop working out," Paltrow told Chelsea Handler on "Chelsea Lately." "At first I panicked, so I would work out a little bit and then I had to lie and be like, 'No I didn't work out.' I'd be on the treadmill and be like, 'I really have to stop this'."

Paltrow's trainer, Tracy Anderson, known for giving her clients "teeny, tiny" bodies, also had a hard time with the actress' weight gain.

"That was tough for me because we've worked so hard on her body," Anderson told New York City's WABC-TV. "She went down from six days a week of training to three, and she ate everything in sight. Fried chicken, mashed potatoes. They filmed in Nashville, so it's a good place to have some comfort food."

Despite all that, Paltrow's bulkier figure was barely discernable from her usual slim frame, and she shed the extra pounds without much effort.

"It didn't take her very long to lose the weight," Anderson said. "It only took her a couple of weeks. It didn't want to be on her anyway. Extra weight isn't something that she owned."

Stars Pack Pounds for Parts

Hollywood's perpetually popular bachelor let his body balloon for 2005's "Syriana." Clooney chowed down on pasta to pack on 35 pounds for his starring role in the political thriller. At a press conference prior to the film's release, he revealed he wanted to bulk up.

"I'm instantly recognizable, so we wanted to change it," he said. "I'm sort of happy at the idea that people when they first see me in the movie, or when they first see the poster don't even know it's me. To me, that makes me proud."

Though Clooney's fuller figure may have contributed to his on-set back injury which required multiple surgeries, ultimately, his weight gain gambit paid off: in 2006, Clooney scored a best supporting actor Oscar for "Syriana."